The present invention relates to an electronic equipment with a vibration alarm and, more particularly, to a stepping motor incorporated in an electronic equipment with a vibration alarm for alarming the user by transmitting vibration to the user""s arm.
As disclosed in Japanese Utility Model Laid-Open Nos. 2-6291 and 2-107089, a conventional wristwatch with a vibration alarm as an electronic equipment for generating vibration by rotating an eccentric weight by a motor incorporates an ultrasonic motor. The rotation of the rotor of the ultrasonic motor is transmitted to an eccentric weight wheel having an eccentric barycentric position. Vibration caused by the rotation of the eccentric weight wheel is transmitted to the user""s arm through the watch case, thereby alarming the user by a vibration alarm.
In the ultrasonic motor of the Japanese Utility Model Laid-Open Nos. 2-6291 and 2-107089, a vibrator bonded with a piezoelectric element is supported by a support pin, and the rotor and the vibrator are brought into tight contact with each other by a compression spring. The operational principle of the ultrasonic motor is to deflect and enlarge the vibration of the piezoelectric element by a comb gear portion provided to the vibrator, to generate a traveling wave in the comb gear portion, and to rotate the rotor by a frictional compression force of the comb gear portion and the rotor.
More specifically, the rotor is rotated while it is constantly urged against the comb gear portion of the vibrator by the compression spring. Then, wear of the contact portion of the rotor and the comb gear portion is unavoidable, providing insufficient durability.
Since the vibration of the piezoelectric element has a small amplitude, the comb gear portion of the vibrator for deflecting and enlarging this amplitude requires especially high machining precision. Hence, it is difficult to machine the comb gear portion of the vibrator. In order to stably rotate the rotor, not only the vibrator but also other components, e.g., the piezoelectric element and the rotor must have high machining precision and high assembling precision.
It is an object of the present invention to provide a reliable small electronic equipment with a vibration alarm (e.g., a wristwatch), which has a rotor having high rotational durability, can be assembled easily, has low power consumption, can be stably started even if an acceleration is applied to it when, e.g., the user swings his arm, and has a stepping motor as a drive source in order to enable high-speed rotation.
In order to achieve the above object, according to the present invention, there is provided an electronic equipment with a vibration alarm, which generates vibration by rotating, with a motor, an eccentric weight having a barycenter at a position deflected from a rotary axis, characterized in that the motor is a flat stator type bipolar stepping motor which comprises a bipolar flat stator, a rotor having a bipolar permanent magnet, and a drive coil magnetically coupled to the flat stator, and in which the eccentric weight is directly fixed to a rotor shaft of the rotor, and the rotor of the flat stator type bipolar stepping motor is rotated to rotate the eccentric weight, thereby generating vibration.
In this electronic equipment with a vibration alarm, the position of the barycenter of the eccentric weight is arranged at a position satisfying 0xc2x0 less than xcex8 less than 90xc2x0 or 180xc2x0 less than xcex8 less than 270xc2x0 when the stator is kept still, where xcex8 is the angle from the position of the barycenter of the eccentric weight to the vertical direction of the gravity along the rotational direction of the eccentric weight about the rotor shaft as the center.
In this electronic equipment with a vibration alarm, the eccentric weight and the rotor magnet are fixed to the rotor shaft such that xcex1 and xcex2 are substantially equal angles where xcex2 is the angle from the barycenter of the eccentric weight to a magnetic pole of the rotor magnet along the rotational direction of the eccentric weight about the rotor shaft as the center and xcex1 is the angle between a slit of the stator of the flat stator type bipolar stepping motor and the vertical direction of the gravity.
This electronic equipment with a vibration alarm is a wristwatch, and the eccentric weight and the rotor magnet are fixed to the rotor shaft such that xcex1 and xcex2 are substantially equal angles where xcex1 is the angle between a slit of the stator of the flat stator type bipolar stepping motor and the direction of 12 o""clock from the center of the dial of the watch.
This electronic equipment with a vibration alarm is a wristwatch and comprises a main plate constituting a timepiece module and a dial having marks. The eccentric weight is arranged on the dial side with the main plate as a boundary. The rotor magnet is arranged on a side opposite to the dial.
This electronic equipment with a vibration alarm is a wristwatch and comprises a main plate constituting a timepiece module and a dial having marks. The eccentric weight is arranged to be adjacent to the main plate. Through holes for exposing part of the eccentric weight are formed in the main plate and the dial.
In this electronic equipment with a vibration alarm, a rotary drive circuit device of the rotor of the flat stator type bipolar stepping motor comprises drive pulse generating means for outputting a pulse signal for driving the stepping motor on the basis of an alarm signal output at alarm time, a drive circuit for supplying a drive current to the drive coil on the basis of the pulse signal supplied from the drive pulse generating means, the flat stator for transmitting a magnetomotive force generated in the drive coil to the rotor, a counter electromotive voltage detection coil for detecting a counter electromotive voltage generated by rotation of the rotor, and magnetic pole position detection means for detecting a magnetic pole position of the rotor, which is rotating, with respect to the flat stator on the basis of the counter electromotive voltage generated in the counter electromotive voltage detection coil, and outputting, to the drive pulse generating means, a detection signal for controlling an output timing of the pulse signal from the drive pulse generating means.
As is apparent from the above aspects, in the electronic equipment of the present invention, a flat stator type bipolar stepping motor which is established in the prior art is utilized. An eccentric weight is directly fixed to the rotor shaft of a rotor constituting the flat stator type bipolar stepping motor. The eccentric weight is rotated by rotating the rotor, so that vibration accompanying rotation of the barycenter of the eccentric weight is generated. Then, the user is alarmed with the vibration.
As described above, according to the present invention, an electronic equipment with a vibration alarm can be constituted by using a flat stator type bipolar stepping motor that can make free use of the prior art providing advanced machining techniques. The eccentric weight is directly fixed to the rotor shaft. The eccentric weight is rotated by rotating the rotor of the flat stator type bipolar stepping motor, thereby generating vibration. Hence, a reliable electronic equipment with a vibration alarm having a rotor of high rotational durability, which can be easily assembled, requires low power consumption, and can be stably rotated, can be provided.
According to the present invention, the position of the barycenter of the eccentric weight is arranged to satisfy 0xc2x0 less than xcex8 less than 90xc2x0 or 180xc2x0 less than xcex8 less than 270xc2x0 when the stator is kept still, where xcex8 is the angle from the position of the barycenter of the eccentric weight to the vertical direction of the gravity along the rotational direction of the eccentric weight about the rotor shaft as the center. Therefore, a reliable electronic equipment with a vibration alarm that can be stably started and rotated even when an acceleration is applied to it by, e.g., the swing of the arm, can be provided.
According to the present invention, the eccentric weight and the rotor magnet are fixed to the rotor shaft such that xcex1 and xcex2 are substantially equal angles where xcex2 is the angle from the barycenter of the eccentric weight to a magnetic pole of the rotor magnet along the rotational direction of the eccentric weight about the rotor shaft as the center and xcex1 is the angle between a slit of the stator of the flat stator type bipolar stepping motor and the vertical direction of the gravity. Therefore, an electronic equipment with a vibration alarm that can be started readily even when an acceleration and a gravitational acceleration caused by the swing of the arm are simultaneously applied to it can be provided.
According to the present invention, an electronic equipment with a vibration alarm that can be started readily even when an acceleration and a gravitational acceleration caused by the swing of the arm are simultaneously applied to it can be provided only by measuring the angle xcex1 between the slit of the stator and the vertical direction of the gravity in advance, providing a mark in advance to part of the eccentric weight at an angle xcex2 from the barycenter of the eccentric weight along a rotational direction C, and fixing the rotor magnet to the rotor shaft by aligning the mark indicating the direction of the magnetic pole of the rotor magnet with the mark of the eccentric weight.
According to the present invention, the worst state wherein the starting operation of the electronic equipment with a vibration alarm is adversely affected the worst is set when the user jogs with the electronic equipment with the vibration alarm on his arm. In this case, the direction of 12 o""clock of the dial of the watch substantially coincides with the vertical direction of the gravitational acceleration. Therefore, an electronic equipment with a vibration alarm that can be started readily even when an acceleration and a gravitational acceleration caused by the swing of the arm are simultaneously applied to it can be provided by fixing the eccentric weight and the rotor magnet to the rotor shaft such that xcex1 and xcex2 are substantially equal angles where xcex1 is the angle between a slit of the stator of the flat stator type bipolar stepping motor and the direction of 12 o""clock from the center of the dial of the watch.
According to the present invention, with reference to the main plate constituting a timepiece module as a boundary, when the eccentric weight is arranged on the dial side and the rotor magnet is arranged on a side opposite to the dial, the module thickness in the periphery of the flat stator type bipolar stepping motor excluding a coil block can be suppressed and flat batteries can be stacked, thereby constituting a low-profile timepiece module.
According to the present invention, the eccentric weight is arranged to be adjacent to the main plate constituting a timepiece module, and through holes for exposing part of the eccentric weight are formed in the main plate and the dial. Therefore, rotation of the eccentric weight can be visually informed to the user other than the vibration accompanying rotation of the barycenter of the eccentric weight.
Furthermore, according to the present invention, there is provided a reliable small electronic equipment with a vibration alarm, having a stepping motor that requires a small power consumption, has a high durability, can be assembled easily, and can be stably started and rotated at a high speed. Especially, this electronic equipment with a vibration alarm has a magnetic pole position detection means for detecting the magnetic pole position of the rotating rotor with respect to the flat stator on the basis of a counter electromotive voltage generated in the counter electromotive voltage detection coil. The drive pulse generating means controls the output timing of the pulse signal on the basis of a detection signal from the magnetic pole position detection means. Therefore, a high-speed stepping motor necessary for the vibration alarm can be realized.
The above and other objects, aspects, and advantages of the present invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiments thereof based on the principle of the present invention with reference to the accompanying drawings.